Chapter 6: Fingerprint Identification

The courtyard of the Criminal Police Team was much quieter than usual.

In a county with a population of several hundred thousand like Ningtai County, there are not many major cases. All year round, there are only ten or eight abnormal deaths, and those that finally become criminal cases, the so-called homicide cases, are about one or two.

Because of this, even if the case seems simple, the Criminal Police Team is in an all-out mode.

When Jiang Yuan returned to the office, he saw that the fourth floor where the Criminal Science Team was located was empty, and only the door of the Trace Examination Office was open, with people busy typing on the keyboard inside.

"Write the report in more detail. This case might lead to a death penalty, and the requirements for death penalty review are very strict." Wu Jun reminded Jiang Yuan and said, "When we did a case back then, a piece of evidence was a plastic oil drum. The case had been handled for two years, but suddenly we received a call asking us why the oil drum in the photo was white, while the actual evidence was yellow."

Jiang Yuan listened while turning on the computer and couldn't help but ask curiously, "Why?"

"Why? Because the actual evidence had been left for a long time, and the plastic had aged. We had to redo the supplementary materials." Wu Jun paused and then said, "I'm telling you this because I want to tell you that the verification of the death penalty is much stricter than other cases. Many eyes are watching, so setting a higher standard doesn't hurt."

"Understood." Jiang Yuan followed suit and asked, "And my relationship with my seventeenth uncle... should I avoid it?"

"Only close relatives need to." The close relatives Wu Jun mentioned have different scopes in different legal provisions. Among them, the scope of administrative law is the widest, and that of criminal law is the narrowest, only including spouses, parents, children, and siblings.

Jiang Yuan felt at ease and worked seriously.

Soon, rows of photos were neatly arranged in front of him.

Seventeenth uncle's intestines, seventeenth uncle's heart, seventeenth uncle's brain slices, seventeenth uncle's stomach contents... Jiang Yuan carefully selected and annotated them clearly.

For the police, the complexity of handling a case is often far better than solving it. Just like the homicide case in front of him, even if the case is simple and clear and the suspect confesses, there are countless document work to be done in the case handling stage.

It was almost time to get off work when noisy sounds came from the courtyard.

Jiang Yuan looked out the window and saw that all three cars of the Criminal Police Team had stopped in. The captain of the second squadron, Liu, was even wearing police equipment, standing in front of the middle police car like a great enemy.

The seventeenth aunt was thin and moved out of the back seat with handcuffs on, her eyes dull.

To be honest, Jiang Yuan had no good or bad memories of his seventeenth aunt. Before taking the civil service exam, he had studied at a medical university in another place for five years, and before the college entrance examination, he had studied at a boarding school for three years. His impression of his seventeenth aunt was far less than his impression of his seventeenth uncle's big belly...

"The suspect identified the murder weapon, which was a chef's knife, thrown into a trash can outside the community." Wu Jun also stood up to look down, and updated the case for Jiang Yuan.

Jiang Yuan breathed a sigh of relief. The case had progressed to this point, and the investigation work was basically over. Especially in this kind of case where the murder weapon was discarded and identified in a different place, the difficulty of overturning the case was more than ten times harder than just having a confession.

"What about abandoning the corpse? She couldn't move it alone." Jiang Yuan asked another question.

"Her younger brother helped move it, using the tricycle and cart for transporting vegetables in the shop." Wu Jun paused and said, "The person was also caught and confessed."

In this way, it was a case with both physical evidence and confession, basically an iron case.

While his mind was wandering, the semi-transparent system interface popped up.

Task: Perform a comprehensive autopsy and assist in solving the case.

Task Reward: Chongqing-style single-finger fingerprint analysis method—Arch pattern identification (LV3).

Jiang Yuan stared wide-eyed, and saw a silver lump flying into his forehead.

Complex information squeezed in frantically.

Chongqing-style single-finger fingerprint analysis method is one of the single-finger fingerprint analysis methods, and it is also the earliest single-finger fingerprint analysis method adopted in China. It is specially used to deal with situations where there is only one finger's fingerprint, or even only one incomplete finger's fingerprint. Similar to it, there are also domestic Qingdao-style single-finger fingerprint analysis methods, foreign Bartley-style single-finger fingerprint classification methods, and many other methods. Different analysis methods cannot be said to be superior or inferior, mainly because the classification and typing of fingerprints are different, and the analysis methods are slightly different.

Simply put, this is a technique used to compare fingerprints.

Jiang Yuan's eyes were slightly bright. Fingerprint comparison can be said to be the housekeeping skill of trace examination, and it is extremely time-consuming and laborious to learn. The system gave it away directly, and he immediately felt his happiness index rise.

However, comparing fingerprints is not an easy task.

The kind of machine that can find matching fingerprints by just entering a random fingerprint photo is non-existent so far.

Internationally mature Automated Fingerprint Identification Systems (AFIS), regardless of whether they use RBNEC, American COGENT, or French Morpho, all use manual marking of on-site fingerprint features, the so-called feature points, and then automatically match and retrieve the fingerprint feature points in the system, and finally give a candidate inspection list based on the degree of similarity from high to low.

This is because fingerprints will appear deformed due to factors such as pressure, and often non-linear deformation. Many times, fingerprints will also appear shifted and covered, and poor preservation conditions are common. Fingerprints found at crime scenes are more likely to be incomplete.

In short, automated fingerprint identification technology requires someone to perform manual pre-processing on fingerprints first.

And equipment like employee punch-in machines only knows how to compare whether two fingerprints are the same, and the recognition rate cannot meet the needs of the police at all.

Wu Jun only saw Jiang Yuan's expression was not focused, and couldn't help but cough twice, saying, "There's nothing else to do. If you want to get off work, go back first. I'll handle the rest."

"Uh... is that okay?" Jiang Yuan hesitated. He wanted to try the newly acquired technology, but going home to try it didn't seem to hinder anything.

"We just have this much work, just finish it." Wu Jun raised his chin proudly. Compared with the police officers who had just started to get busy below, the busyness of the forensic doctor had already ended.